Numerical Analysis on the Leading Edge Film Cooling of Bifurcation Holes for Gas Turbine Blade

2021 ◽  
Author(s):  
Zhonghao Tang ◽  
Gongnan Xie ◽  
Honglin Li ◽  
Wenjing Gao ◽  
Chunlong Tan ◽  
...  
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Turbulence Models ◽  
Leading Edge ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Cylindrical Holes ◽  
Lift Off

Abstract Film cooling performance of the cylindrical film holes and the bifurcated film holes on the leading edge model of the turbine blade are investigated in this paper. The suitability of different turbulence models to predict local and average film cooling effectiveness is validated by comparing with available experimental results. Three rows of holes are arranged in a semi-cylindrical model to simulate the leading edge of the turbine blade. Four different film cooling structures (including a cylindrical film holes and other three different bifurcated film holes) and four different blowing ratios are studied in detail. The results show that the film jets lift off gradually in the leading edge area as the blowing ratio increases. And the trajectory of the film jets gradually deviate from the mainstream direction to the spanwise direction. The cylindrical film holes and vertical bifurcated film holes have better film cooling effectiveness at low blowing ratio while the other two transverse bifurcated film holes have better film cooling effectiveness at high blowing ratio. And the film cooling effectiveness of the transverse bifurcated film holes increase with the increasing the blowing ratio. Additionally, the advantage of transverse bifurcated holes in film cooling effectiveness is more obvious in the downstream region relative to the cylindrical holes. The Area-Average film cooling effectiveness of transverse bifurcated film holes is 38% higher than that of cylindrical holes when blowing ratio is 2.

Enhancement of Film Cooling Performance at the Leading Edge of Turbine Blade

2006 ◽  
Author(s):  
K.-S. Kim ◽  
Youn J. Kim ◽  
S.-M. Kim
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Cylindrical Body ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio

To enhance the film cooling performance in the vicinity of the turbine blade leading edge, the flow characteristics of the film-cooled turbine blade have been investigated using a cylindrical body model. The inclination of the cooling holes is along the radius of the cylindrical wall and 20 deg relative to the spanwise direction. Mainstream Reynolds number based on the cylinder diameter was 1.01×105 and 0.69×105, and the mainstream turbulence intensities were about 0.2% in both Reynolds numbers. CO2 was used as coolant to simulate the effect of density ratio of coolant-to-mainstream. Furthermore, the effect of coolant flow rates was studied for various blowing ratios of 0.4, 0.7, 1.1, and 1.4, respectively. In experiment, spatially-resolved temperature distributions along the cylindrical body surface were visualized using infrared thermography (IRT) in conjunction with thermocouples, digital image processing, and in situ calibration procedures. This comparison shows the results generated to be reasonable and physically meaningful. The film cooling effectiveness of current measurement (0.29 mm × 0.33 min per pixel) presents high spatial and temperature resolutions compared to other studies. Results show that the blowing ratio has a strong effect on film cooling effectiveness and the coolant trajectory is sensitive to the blowing ratio. The local spanwise-averaged effectiveness can be improved by locating the first-row holes near the second-row holes.

Mechanism of Film Cooling with One Inlet and Double Outlet Hole Injection at Various Turbulence Intensities

2018 ◽  
Vol 35 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Guangchao Li ◽  
Yukai Chen ◽  
Zhihai Kou ◽  
Wei Zhang ◽  
Guochen Zhang
Keyword(s):  
Turbulence Intensity ◽  
Film Cooling ◽  
Hole Injection ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Outlet Hole ◽  
Cylindrical Holes ◽  
High Turbulence

AbstractThe trunk-branch hole was designed as a novel film cooling concept, which aims for improving film cooling performance by producing anti-vortex. The trunk-branch hole is easily manufactured in comparison with the expanded hole since it consists of two cylindrical holes. The effect of turbulence on the film cooling effectiveness with a trunk-branch hole injection was investigated at the blowing ratios of 0.5, 1.0, 1.5 and 2.0 by numerical simulation. The turbulence intensities from 0.4 % to 20 % were considered. The realizable$k - \varepsilon $turbulence model and the enhanced wall function were used. The more effective anti-vortex occurs at the low blowing ratio of 0.5 %. The high turbulence intensity causes the effectiveness evenly distributed in the spanwise direction. The increase of turbulence intensity leads to a slight decrease of the spanwise averaged effectiveness at the low blowing ratio of 0.5, but a significant increase at the high blowing ratios of 1.5 and 2.0. The optimal blowing ratio of the averaged surface effectiveness is improved from 1.0 to 1.5 when the turbulence intensity increases from 0.4 % to 20 %.

Leading Edge Film Cooling of a Turbine Blade Model Through Single and Double Row Injection: Effects of Coolant Density

1994 ◽  
Author(s):  
M. Salcudean ◽  
I. Gartshore ◽  
K. Zhang ◽  
Y. Barnea
Keyword(s):  
Turbine Blade ◽  
Mass Flow ◽  
Film Cooling ◽  
Leading Edge ◽  
Spanwise Direction ◽  
Double Row ◽  
Cooling Effectiveness ◽  
Stagnation Line ◽  
Film Cooling Effectiveness ◽  
Staggered Arrangement

Experiments have been conducted on a large model of a turbine blade. Attention has been focussed on the leading edge region, which has a semi-circular shape and four rows of film cooling holes positioned symmetrically about the stagnation line. The cooling holes were oriented in a spanwise direction with an inclination of 30° to the surface, and had streamwise locations of ±15° and ±44° from the stagnation line. Film cooling effectiveness was measured using a heat/mass analogy. Single row cooling from the holes at 15° and 44° showed similar patterns: spanwise averaged effectiveness which rises from zero at zero coolant mass flow to a maximum value η* at some value of mass flow ratio M*, then drops to low values of η at higher M. The trends can be quantitatively explained from simple momentum considerations for either air or CO2 as the coolant gas. Close to the holes, air provides higher η values for small M. At higher M, particularly farther downstream, the CO2 may be superior. The use of an appropriately defined momentum ratio G collapses the data from both holes using either CO2 or air as coolant onto a single curve. For η*, the value of G for all data is about 0.1. Double row cooling with air as coolant shows that the relative stagger of the two rows is an important parameter. Holes in line with each other in successive rows can provide improvements in spanwise averaged film cooling effectiveness of as much as 100% over the common staggered arrangement. This improvement is due to the interaction between coolant from rows one and two, which tends to provide complete coverage of the downstream surface when the rows are placed correctly with respect to each other.

Simulation Film Cooling in the Leading Edge Region of a Turbine Blade (Trench Effect on Film Effectiveness from Cylinder in Crossflow)

2014 ◽  
Vol 554 ◽  
pp. 317-321
Author(s):  
Mohamad Rasidi Bin Pairan ◽  
Norzelawati Binti Asmuin ◽  
Hamidon bin Salleh
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Edge Region ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Hot Gas ◽  
Cooling Technique

Film cooling is one of the cooling techniques applied to the turbine blade. Gas turbine used film cooling technique to protect turbine blade from directly expose to the hot gas to avoid the blade from defect. The focus of this investigation is to investigate the effect of embedded three difference depth of trench at coolant holes geometry. Comparisons are made at four difference blowing ratios which are 1.0, 1.25 and 1.5. Three configuration leading edge with depth Case A (0.0125D), Case B (0.0350D) and Case C (0.713D) were compared to leading edge without trench. Result shows that as blowing ratio increased from 1.0 to 1.25, the film cooling effectiveness is increase for leading edge without trench and also for all cases. However when the blowing ratio is increase to 1.5, film cooling effectiveness is decrease for all cases. Overall the Case B with blowing ratio 1.25 has the best film cooling effectiveness with significant improvement compared to leading edge without trench and with trench Case A and Case C.

The Experimental and Numerical Research for Linear Cascade Film Cooling With Different Hole Shapes

2010 ◽  
Author(s):  
Yi Lu ◽  
Yinyi Hong ◽  
Zhirong Lin ◽  
Xin Yuan
Keyword(s):  
Film Cooling ◽  
Large Scale ◽  
Leading Edge ◽  
Suction Side ◽  
Pressure Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Linear Cascade ◽  
Blowing Ratio ◽  
Cylindrical Holes

Detailed film cooling effectiveness distributions were experimentally obtained on a turbine vane platform within a linear cascade. Testing was done in a large scale five-vane cascade with low freestream Renolds number condition 634,000 based on the axial chord length and the exit velocity. The detailed film-cooling effectiveness distributions on the platform were obtained using pressure sensitive paint technique. Two film-cooling hole configurations, cylindrical and fan-shaped, were used to cool the vane surface with two rows on pressure side, two rows on suction side and three rows on leading edge. For cylindrical holes, the blowing ratio of the coolant through the discrete cooling holes on pressure side and suction side ranged from 0.3 to 1.5 (based on the inlet mainstream velocity) while the blowing ratio ranging from 0.15 to 1.5 on leading edge; for fan-shaped holes, the four blowing ratios were 0.5, 1.0, 1.5 and 2.0. Results showed that average film-cooling effectiveness decreased with increasing blowing rate for the cylindrical holes, while the fan-shaped passage showed increased film-cooling effectiveness with increasing blowing ratio, indicating the fan-shaped cooling holes helped to improve film-cooling effectiveness by reducing overall jet liftoff. Fan-shaped holes improved average film-cooling effectiveness by 93.2%, 287.6% and 489.6% on pressure side, −4.1%, 27.9% and 78.2% on suction side over cylindrical holes at the blowing ratio of 0.5, 1.0 and 1.5 respectively. Numerical results were used to analyze the details of the flow and heat transfer on the cooling area with two turbulence models. Results demonstrated that tendency of the film cooling effectiveness distribution of numerical calculation and experimental measurement was generally consistent at different blowing ratio.

Adiabatic Film Cooling Effectiveness of a LAM Fabricated Porous Leading Edge Segment of a Turbine Blade

2018 ◽  
Author(s):  
Luisana Calderon ◽  
Andres Curbelo ◽  
Gaurav Gupta ◽  
Jayanta S. Kapat
Keyword(s):  
Additive Manufacturing ◽  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Metal Powders ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Porous Region ◽  
External Cooling

Laser additive manufacturing (LAM) is an emerging technology that builds parts in a layer-by-layer process by selectively melting metal powders. This additive manufacturing technique among others can produce very complex geometries, which are not possible using conventional methods. A mock segment of the leading edge of a turbine blade, designed with both internal and external cooling features fabricated by LAM of Inconel powder, is investigated. This design consists of an internal impingement cooling array and an engineered-porous structure. This porous region consists of a lattice of intersecting cylinders that simulates the effect of a transpiration cooled segment or permeable wall with a designed porosity of 0.57. Transpiration cooling is a promising external cooling technique capable of reducing thermal gradients at the surface of the blade by providing a more uniform film than conventional discrete film cooling holes. In this current study, adiabatic film cooling effectiveness is experimentally investigated using pressure sensitive paint (PSP) for blowing ratios ranging between 0.03 and 0.15. Using air as the mainstream, and CO2 as the coolant source, a density ratio of 1.5 is obtained. Steady state simulations using RANS are analyzed and used to compare against experimental results. All cases result in an increase in effectiveness values with increasing blowing ratio. Highest effectiveness values are associated with high pressure drop. Coolant uniformity is observed downstream the porous region and mixing becomes more significant as blowing ratio is increased.

The Effect of Conjugate Heat Transfer on Film Cooling Effectiveness

Volume 4 ◽  
2004 ◽  
Author(s):  
Mahmood Silieti ◽  
Eduardo Divo ◽  
Alain J. Kassab
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Turbulence Models ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Effectiveness Prediction ◽  
Lift Off ◽  
Rsm Model

We investigate the numerical prediction of film cooling effectiveness of a two-dimensional gas turbine endwall for the cases of conjugate and adiabatic heat transfer models. Further, the consequence of various turbulence models employed in the computation are investigated by considering various turbulence models: ‘RNG’ k-ε model, Realizable k-ε model, Standard k-ω model, ‘SST’ k-ω model, and ‘RSM’ model. The computed flow field and surface temperature profiles along with the film effectiveness for one and two cooling slots at different injection angles and blowing ratio of one are presented. The results show the strong effect of the conjugate heat transfer on the film effectiveness compared to the adiabatic and analytically derived formulae and show that turbulence model used significantly affects the film effectiveness prediction when separation occurs in the film hole and some level of jet lift-off is present.

Investigation on the Leading Edge Film Cooling of Counter-Inclined Cylindrical and Laid-Back Holes With and Without Impingement: Part I — Film Cooling Effectiveness

2018 ◽  
Author(s):  
Qi-ling Guo ◽  
Cun-liang Liu ◽  
Hui-ren Zhu ◽  
Hai-yong Liu ◽  
Rui-dong Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Cylindrical Hole ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Turbine Vane

Experimental investigation has been performed to study the film cooling characteristics of counter-inclined structures on the turbine vane leading edge. In this paper, four counter-inclined models are measured including cylindrical film holes with and without impingement holes, laid-back film holes with and without impingement holes. A semi-cylinder model is used to model the turbine vane leading edge. Two rows of film holes are located at ±15° on either side of the leading edge model, inclined 90° to the flow direction and 45° to the spanwise direction. Film cooling effectiveness and heat transfer coefficient have been obtained using a transient heat transfer measurement technique with double thermochromic liquid crystals with four blowing ratios ranging from 0.5 to 2 at a 1.0 density ratio. The results show that the film cooling effectiveness decreases with the increase of blowing ratio. No matter cylindrical hole or laid-back hole, the addition of impingement enhances the film cooling effectiveness. Compared with cylindrical hole, laid-back hole produces a better film cooling performance mainly because of stronger lateral momentum. Moreover, the benefits of both adding impingement and exit shaping are more obvious under a large blowing ratio.

Numerical Evaluation of the Performance of the Sister–Shaped Single–Hole Schemes on Turbine Blade Leading Edge Film Cooling

2015 ◽  
Author(s):  
Siavash Khajehhasani ◽  
Bassam Jubran
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Numerical Evaluation ◽  
Leading Edge ◽  
Lateral Spread ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Hole ◽  
Shaped Hole ◽  
Lift Off

In the present study, a numerical evaluation of the performance of the sister-shaped single-hole (SSSH) schemes (downstream, upstream and up/downstream) on the leading edge of AGTB-B1 high pressure turbine blade cascade is carried out. Simulations are performed at three blowing ratios of 0.7, 1.1 and 1.5. Predicted results are compared to the single cylindrical hole and a 15° forward-diffused shaped hole. The realizable k-ε model combined with the standard wall function is used to model the flow field; wherein, the predicted pressure field was in a good agreement with the available experimental data. At the high blowing ratios of 1.1 and 1.5, a noticeable improvement in the film cooling effectiveness and the lateral spread of the cooling jet has been observed for the upstream and up/downstream SSSH schemes, in particular on the suction side. The downstream SSSH configuration provided almost similar film cooling effectiveness values to that of the forward diffused shaped hole for all blowing ratios on both the pressure and suction sides of the blade. Note that the obtained film cooling effectiveness for the downstream SSSH scheme at high blowing ratios was disappointing in comparison with other SSSH schemes where much higher film cooling effectiveness values were obtained. The mixing of the coolant with the high mainstream flow at the leading edge of the blade is considerably decreased for the upstream and up/downstream SSSH schemes and more adhered coolant to the blade’s surface is observed than with other configurations. Moreover, the jet lift-off is notably diminished for the upstream and up/downstream SSSH compared to other hole geometries.

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